Retail transactions such as purchases may be performed with payment devices such as a credit card or a NFC-enabled smart phone running a payment application. A traditional payment terminal may reside at a fixed location and may have a physical connection to a power source such as an AC outlet. The payment terminal may also be physically connected to a wired communication interface such as a phone line or Ethernet connection. The payment terminal receives payment information such as a credit card number from the payment device and communicates with a remote server such as a payment server to determine whether the transaction is approved.
Such a traditional payment terminal may not be suitable for many businesses. Taxis, food trucks, delivery services, professional service providers, and other similar businesses engage in transactions from a vehicle or at disparate locations. Applications running on a mobile device such as smart phone or tablet may provide a user interface to facilitate payment transactions and a communication interface for communicating with the payment server. However, a separate payment reader may be necessary in order to interface with the payment device. The payment reader and mobile device may communicate wirelessly. The payment reader and mobile device may exchange a large volume of data in order to process payment transactions, provide software updates to the payment reader, and otherwise interface between the two devices.